In projector technology, x-prisms are typically used to combine red, green, and blue light into a full composite image.
Referring to FIGS. 6-7, an x-prism 10 is composed of a first triangular prism 101, a second triangular prism 102, a third triangular prism 103, and a fourth triangular prism 104. Each of the triangular prisms has a same configuration, and a same right-angle formed therebetween. The first triangular prism 101 provides a hypotenuse side 1011, a first side 1012, a second side 1013 perpendicular to the first side 1012, and a polished side 1014. The hypotenuse side 1011 is connected to the first side 1012 and the second side 1013. The polished side 1014 is adjoining the hypotenuse side 1011, the first side 1012, and the second side 1013. The first triangular prisms 101, the second triangular prism 102, the third triangular prism 103, and the fourth triangular prism 104 are closely adhered each other via adhering the corresponding rectangular sides thereof, thereby the x-prism 10 is formed.
When different color lights are transmitted through the x-prism 10, such as a red incident light 111 transmitting through the hypotenuse side 1011 of the triangular prism 101, a green incident light 112 transmitting through the corresponding hypotenuse side of the triangular prism 102, and a blue incident light 113 transmitting through the corresponding hypotenuse side of the triangular prism 103, they are combined to form a full composite image emitted from the corresponding hypotenuse side of the triangular prism 104. Moreover, the first side 1012 and the second side 1013 of the triangular prism 101 respectively provides a first coating 106 and a second coating 105 with different properties from the first coating 106. The second coating 105 allows any color incident light except the red incident light 111 to transmit through the x-prism 10, and the first coating 106 allows any color light except the blue incident light 113 to transmit through the x-prism 10. The corresponding first and second sides of one of the second triangular prism 102, the third triangular prism 103, and the fourth triangular prism 104 also respectively provides different coatings with different properties.
The x-prism 10 provides the polished sides as an orientation base for configuring the x-prism 10 to the projector. The polished sides of the x-prism 10 are assembled to the projector by adhesives. In a high-temperature environment, the adhesive bond between the x-prism and the projector may weaken and cause a shifting of position of the triangular prisms of the x-prism device, negatively affecting image resolution.